Analysis of Dynamic Load Tests on Reinforced Foundations Under the Influence of Karst Soil Cavity Collapse

Karst soil caves are prone to induce insufficient bearing capacity and excessive settlement of engineering foundations, which in turn trigger sudden ground surface collapse. In this study, multi-stage cyclic loads were designed to simulate traffic loads, and model tests were conducted to measure and analyze the variation laws of foundation settlement, peak vertical earth pressure within the foundation, and reinforcement strain at different positions under cyclic dynamic loading. The results show that the following: ① under cyclic dynamic loading, the collapse of soil caves significantly reduces the bearing capacity of reinforced foundations with an influence range of up to 3B; ② affected by karst soil caves, reinforced foundations only experience a short elastic compaction stage under cyclic loading, followed by rapid deformation until failure; ③ a critical value exists in the earth pressure distribution at a distance of 1B–2B from the soil cave to the foundation center, which governs the abrupt pressure drop behavior in the collapse zone; ④ under the same level of cyclic loading, the height and number of soil arches are independent of the number of loading cycles, and the soil arching effect exerts the most significant influence on the bearing capacity of reinforced foundations at the initial stage of loading application.